Protein-protein interactions and assembly of multiprotein assemblies within cells are a core theme running throughout biology, e.g., mitochondrial multienzyme protein assemblies and multiprotein assemblies for bacterial polyketide and other secondary metabolite synthesis. However spatially controlled assembly of multiple protein actors in vitro, e.g., for the generation of artificial biosynthetic pathways, remains a daunting challenge. In particular, there is an ongoing need for methods and compositions that allow controlled spatial localization of proteins ex vivo on artificial substrates, e.g., in protein arrays or 3D scaffolds.